1. Field of the Invention
The present invention relates to a process cartridge, and an image forming apparatus having a process cartridge. The present invention also relates to a main cartridge which a sub cartridge can be attached to and detached from, and a sub cartridge that can be attached to and detached from the main cartridge.
2. Description of the Related Art
An image forming apparatus employing an electrophotographic technology selectively exposes an image bearing member (hereinafter, referred to as photosensitive drum) uniformly charged by a charging device to light using an exposure device to form a latent image on the photosensitive drum. Further, the image forming apparatus develops the latent image with developer (toner) using a development device, transfers the developed image on a recording medium, and presses and heats the transferred image on the recording medium using a fixing device, and thus the image recording is performed.
In such an electrophotographic image forming apparatus, during the use of the apparatus, maintenance such as toner supply and adjustment and replacement of parts is required. To ease the maintenance work, there is a technique, as a replacement unit, a main cartridge and a sub cartridge is provided such that the sub cartridge can be attached to and detached from the main cartridge. The main cartridge is attached to an apparatus body of an image forming apparatus.
For example, Japanese Patent Application Laid-Open No. 2005-258024 provides a technique that has been in practical use in which, as a sub cartridge, a toner bottle (developer cartridge) containing toner is integrated as a unit, and as a main cartridge, a cartridge (development cartridge) having a development device is integrated as a unit, respectively. The developer cartridge can be attached to and detached from the development cartridge, and the development cartridge having the developer cartridge can be attached to and detached from the apparatus body of the image forming apparatus.
In such a technique, there is a possibility that only the development cartridge is attached to the image forming apparatus without attaching the developer cartridge to the development cartridge, and the image forming apparatus is operated. If the image forming apparatus is operated in such a state where only the development cartridge is attached, the toner is not supplied to the development device having the development cartridge, and as a result, the image formation is not properly performed.
To solve the problem, a detection device for detecting whether the developer cartridge is attached to the image forming apparatus body can be provided to notify the user that the developer cartridge is not attached with a lamp or display screen on an operation unit. However, the installation of the device complicates the structure of the apparatus body, and further, the notification can be issued only after the cartridge is attached to the apparatus body.